Field of the Invention
The present invention relates to a radiation imaging system including a radiation imaging apparatus configured to obtain a captured image by radiographic image capturing of a subject, and an external apparatus configured to be connectable to the radiation imaging apparatus, and also relates to a control method therefor and a storage medium having stored thereon a program for executing the control method.
Description of the Related Art
There have hitherto been known radiation imaging apparatus products and radiation imaging system products in which a radiation generation apparatus irradiates a subject with a radiation ray, the intensity distribution of a portion of the radiation ray that is transmitted through the subject is converted into digital signals to generate a radiographic image that is a captured image, and image processing is performed on the radiographic image to obtain a sharp radiographic image.
In such radiation imaging systems, a radiation generation apparatus emits a radiation ray and a radiation imaging apparatus transfers image data of a generated radiographic image to an image processing apparatus such as a control computer for image processing and saving.
A radiation imaging apparatus generally includes a sensor array in which pixels are arranged two-dimensionally and each pixel includes a conversion element configured to convert radiation into signal charges (electric signals) and a switching element, such as a TFT, configured to transfer the electric signals to the outside. The radiation imaging apparatus executes matrix driving with the use of the switching element such as a TFT, to thereby read signal charges generated by the conversion in the conversion element and form a radiographic image from digital signals based on the charge amount of the read signal charges.
In recent years, technologies with which a radiation imaging apparatus itself detects the start/end of radiation irradiation have been proposed, and an example of the technologies can be found in Japanese Patent Application Laid-Open No. 2011-249891. Those technologies eliminate the need for a mechanism that synchronizes the radiation imaging apparatus and the radiation generation apparatus. As a result, the construction of the radiation imaging apparatus is simplified and cable connection between the radiation imaging apparatus and the radiation generation apparatus is rendered unnecessary. A rechargeable battery included inside the radiation imaging apparatus also makes it unnecessary to connect a power supply cable for the feeding of power, thereby improving the portability of the radiation imaging apparatus further.
In Japanese Patent Application Laid-Open No. 2002-190584, there has been proposed an apparatus configured to record image information obtained by image capturing with the use of a portable memory that is removably mounted to the main body of a radiation imaging apparatus. In Japanese Patent Application Laid-open No. 2002-248095, there has been proposed an apparatus configured to transfer, when loaded in a cradle capable of charging a battery of an imaging apparatus, a captured image to an external apparatus via the cradle. Apparatus as those do not need to connect a cable for image transfer or build a wireless communication environment, and can accordingly be built even more simply and are improved in the portability of the imaging apparatus itself.
However, it is difficult with those apparatus to identify the situation of the image capturing that has produced the transferred image information. Identifying the image capturing information of a handed over image can be particularly difficult when images of different subjects captured by a plurality of imaging apparatus or under different image capturing conditions are transferred after a long time.
An apparatus designed to solve this problem has been proposed in, for example, Japanese Patent Application Laid-Open No. 2009-219585. Specifically, the proposed apparatus attempts to solve the problem by controlling a cradle that is capable of loading a plurality of imaging apparatus therein so that only one of the imaging apparatus that is selected by an image capturing order can be used, while the unselected imaging apparatus are locked to prevent removal from the cradle.
In Japanese Patent Application Laid-Open No. 2012-35009, there has been proposed a technology in which a memory is provided in a battery apparatus configured so as to be removably mounted to an imaging apparatus, image capturing information of scheduled image capturing is stored in the memory in advance at the time the battery is charged, and image data is saved in association with the image capturing information when the image is captured. This technology can prevent wrong association between a captured image obtained by image capturing and image capturing information that includes patient information and image capturing conditions.
In Japanese Patent Application Laid-Open No. 2009-219585 and Japanese Patent Application Laid-Open No. 2012-35009, wrong association between image capturing information that includes, for example, patient information, and a captured image itself is avoided by determining which radiation imaging apparatus is to be used based on an image capturing order received in advance. However, it can easily happen in an emergency case or the like that image capturing is demanded without the advance submission of an image capturing order or the advance entering of patient information. In such cases, image capturing information needs to be associated with image data at a separate time after the image data is obtained.
A possible way to accomplish this includes recording, together with the captured image data, image capturing execution information that can be recorded without the advance input, such as the ID of the imaging apparatus that has been used for the image capturing, a captured image ID, and time information about the date/time of execution of the image capturing, and, when the captured image data is transferred subsequently, manually adding image capturing information such as patient information based on those pieces of image capturing execution information.
Of the pieces of information that can be recorded without the advance input, the time information about the date/time of execution of the image capturing is particularly useful in associating the image capturing information later. However, there is a fear in that the time kept by an internal clock of a radiation imaging apparatus does not match a system time on an external apparatus to which the image is transferred, and there may accordingly be a disparity between the system time and the time information about the date/time of image capturing. In the case where image capturing is executed with the use of a plurality of imaging apparatus, in particular, times that are indicated by recorded pieces of image capturing time information may not match the actual order of image capturing because the amount of the disparity of the internal clock varies from one imaging apparatus to another. This can invite confusion when image capturing information that includes patient information (subject information) is manually associated later.
Providing each imaging apparatus with a highly precise clock such as an atomic clock could be a solution, but this complicates the structure of the imaging apparatus. In addition, constantly securing a radio wave environment to correct time is difficult for radiation imaging apparatus, which are used mostly in a room structured so as to cut off radiation because of their nature.